Transgenic snakes and methods of making

ABSTRACT

A transgenic animal such as a transgenic snake or other reptile that expresses a heterologous expression product is described, along with methods of making the same. In general, the animal comprises cells containing a sequence encoding the heterologous expression product. The sequence encoding the heterologous expression product is integrated into the genome of the animal (e.g., in some or all cells thereof, and in some embodiments into germ cells thereof). The sequence encoding the heterologous expression product is, in general, operatively associated with an expression sequence or promoter. The animals are useful for, among other things, testing of repellents, testing of toxicological compounds, as teaching aids, for venom production, etc.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/802,985; Filed May 24, 2006, and of U.S. ProvisionalPatent Application No. 60/829,060; Filed Oct. 11, 2006, the disclosuresof both of which are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present invention is concerned with transgenic animals and the usethereof for (among other things) animal repellent screening,environmental and toxicological testing, production of therapeuticproteins, and classroom teaching aids.

BACKGROUND OF THE INVENTION

Since the initial introduction of transgenic animals as models fordisease (see, e.g., U.S. Pat. No. 5,925,803 to Leder), transgenicanimals have been found useful for a variety of different purposes.

Transgenic non-human mammals have been described for the production oftherapeutic proteins of interest that can be collected from, forexample, milk. See, e.g., U.S. Pat. Nos. 6,344,596; 6,339,183;6,255,554; 6,204,431; 6,166,288; and 5,959,171.

Transgenic frogs have been described as useful for the detection ofendocrine disrupters in the environment. See, e.g., US PatentApplication Publication 2006/0101528, Transgenic frogs have also beendescribed as a model for evaluating drug efficacy. See, e.g., U.S. Pat.No. 5,932,780.

Transgenic birds have been described as useful for, among other things,the production of exogenous proteins that can be collected from eggslaid by such birds. See, e.g., U.S. Pat. No. 6,730,822.

Transgenic zebrafish have been described as useful for developmentalstudies and the testing of toxic compounds, and as classroom teachingaids. See, e.g., U.S. Pat. No. 6,380,458. Transgenic zebrafishexpressing a fluorescent protein are commercially available as theGLOFISH® from the Carolina Biological Supply Company (Burlington, N.C.,USA).

Transgenic mice and certain other animals that express light-emittingfusion proteins are suggested for diagnostic and therapeutic purposes(e.g., drug screening and discovery) in W. Kaelin et al., U.S. Pat. No.7,176,345.

SUMMARY OF THE INVENTION

Reptiles are a geographically widely dispersed group of animals with anumber of interesting attributes, and accordingly represent anattractive population for the development of transgenic animals.Unfortunately, little work has been done to date in developingtransgenic reptiles. Accordingly there is a need for new approaches tothe production of transgenic reptiles, and particularly transgenicsnakes.

The present invention provides a transgenic reptile, such as atransgenic snake, lizard, turtle, tortoise, or crocodilian. The reptileexpresses a heterologous expression product. In general, the reptilecomprises, consists of or consists essentially of cells containing asequence encoding the heterologous expression product. The sequenceencoding the heterologous expression product is integrated into thegenome of the reptile (e.g., in some or all cells thereof, and in someembodiments into germ cells thereof). The sequence encoding theheterologous expression product is, in general, operatively associatedwith an expression sequence or promoter.

In some embodiment the expression product is a reporter protein such asa fluorescent or luminescent protein. In some embodiments the reptilehas a phenotype of fluorescence or luminescence not found in thecorresponding wild-type snake.

In some embodiments the expression product is a therapeutic protein. Insome embodiments the therapeutic protein is expressed into albumin ofeggs laid by the reptile (e.g., by expression in the oviduct or intoovalbumin).

In some embodiments the expression product is stable and transmittedthrough the germline thereof. In some embodiments the expression productis expressed in skin, muscle (e.g., skeletal muscle) or both.

The present invention is explained in greater detail in the drawingsherein and the specification set forth below. The disclosures of allpatent references cited herein are to be incorporated by referenceherein in their entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Polymerase chain reaction (PCR) results from transgenic ballpython skin. All samples indicate a predicted 118 base pair PCR productand a ˜600 bp PCR product. Water control lane shows no amplificationproducts. Lane 1, 1 kb ladder; Lane 2, negative control, dH₂O; Lane 3,Head—Dorsal; Lane 4, Mid-section—Dorsal; Lane 5, Tail—Dorsal; Lane 6,Head—Ventral; Lane 7, Mid-section—Ventral; Lane 8, Tail—Ventral; Lane 9,Positive control eGFP amplification.

FIG. 2. PCR Results from two transgenic ball pythons (lanes 2-7 andlanes 11-16), positive control plasmid (Lane 10), negative controlwild-type ball python DNA (lane 9), and water negative control (lane10). FIG. 2 is a repeat of data presented in FIGS. 1 and 3. Lane 1, 1 kbladder; Lane 2, Head—Dorsal A; Lane 3, Head—Ventral A; Lane 4,Mid-section—Dorsal A; Lane 5, Mid-section—Ventral A; Lane 6, Tail—DorsalA; Lane 7, Tail—Ventral A Lane 8, Negative—dH₂O; Lane 9,Negative—Wild-type; Lane 10, Positive—pMIEM; Lane 11, Head—Dorsal B;Lane 12, Head—Ventral B; Lane 13, Mid-Section—Dorsal B; Lane 14,Mid-Section—Ventral B; Lane 15, Tail—Dorsal B; Lane 16, Tail—Ventral B;Lane 17, 1 kb ladder.

FIG. 3. PCR results from the second transgenic ball python. Lane 1, 1 kbladder; Lane 2, negative control dH₂O; Lane 3, Head—Ventral; Lane 4,Head—Dorsal; Lane 5, Mid-section—Ventral; Lane 6, Mid-section—Dorsal;Lane 7, Tail—Ventral; Lane 8, Tail—Dorsal; Lane 9, Positive control eGFPamplification.

FIG. 4. Verification of DNA integrity of the DNA template used togenerate the data presented in FIGS. 1 and 2. Transgenic Ball PythonDNA. Lane 1, 1 kb ladder; Lane 2, Head—Ventral; Lane 3, Head—Dorsal;Lane 4, Mid-section—Ventral; Lane 5, Mid-section—Dorsal; Lane 6,Tail—Ventral; Lane 7, Tail—Dorsal.

FIG. 5. Verification of DNA integrity of the DNA template used togenerate the data presented in FIGS. 1 and 2. Transgenic Ball PythonDNA: Lane 1, 1 kb ladder; Lane 2, Head—Dorsal; Lane 3, Head—Dorsal; Lane4, Mid-section—Dorsal; Lane 5, Mid-section—Dorsal; Lane 6, Tail—Dorsal;Lane 7, Tail—Dorsal; Lane 8, Head—Ventral; Lane 9, Head—Ventral; Lane10, Mid-section—Ventral; Lane 11, Mid-section—Ventral; Lane 12,Tail—Ventral; Lane 13, Tail—Ventral; Lane 14, 1 kb ladder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

“Reptile” as used herein includes animals of the class Sauropsida, andparticularly animals of the orders Squamata (lizards, snakes andamphisbaenids (worm-lizards), Chelonia or Testudines (turtles)Crocodilia (crocodiles, caimans and alligators), and Rhynchocephalia(tuatars from New Zealand). Particularly preferred are snakes (suborderSerpente) and lizards (suborder Sauria).

“Snake” as used herein may be any snake, including snake families Boids,Colubridae, and Xenopeltidae (sunbeam snakes). Specific examples includebut are not limited to Python regius (Ball Python), Python molurus(Burmese Python), Python sebae (African Rock Python), Python reticulatus(Reticulated Python), Python curtus (Blood Python), Liasis mackloti(Macklott's Python), Antaresia maculosa (Australian Spotted Python),Antaresia childreni (Childrens Python), Morelia spilt (Carpet Pythons),Morelia viridis (Green Tree Pythons), Lampropeltis triangulum,Lampropeltis getulus, Lampropeltis mexicana, Lamporpeltis calligaster,Lamporpeltis doliata (Scarlet King), Lampropeltis alterna, Elapheguttata (Corn Snake), Elaphe obsolete (Rat Snake), Elaphe vulpina (FoxSnake), Elaphe flavirufra (Central American Rat Snake), Elaphe bairdibairds (Rat Snake), Bogertophis subocularis (Trans-Pecos Ratsnake),Bogertophis rosaliae (Baja Ratsnake), Elaphe Elena (Trinket Snake),Liasis fuscus (Water Python), Liasis olivaceus (Olive Python), Liasispapuanus (Papuan Python), Aspidites ramsayi (Woma), Aspiditeselanocephalus (Black Headed Python), Pituophis Melanoleucus (PineSnake), Pituophis Sayi (Bull Snake), Pituophis catenifer (Gopher Snake),Heterodon nasicus (Western Hognose), Heterodon platyrhinos (EasternHognose), Heterodon Simus (Southern Hognose), Xenopeltis hainanensis(Sunbeam Snakes), and Xenopeltis unicolor (Sunbeam Snakes).

In some embodiments the snake is a colubrid snake such as a Kingsnake ormilk snake, such as a common Kingsnake or Lampropeltis getula (e.g.,California Kingsnake or Lamropeltis getula californiae; EasternKingsnake or Lampropeltis getula getula; Florida Kingsnake orlampropeltis getulafloridana etc.), or other members of the genusLampropeltis.

“Lizards” as used herein may be any lizard, including but not limited tothose of lizard families Iguanidae, Agamadae, Geckonidae, Varanidae, andTeiidae. Specific examples include but are not limited to: Iguana iguana(Green Iguana), Cyclura nubila or Cyclura lewisi (Blue Iguana), Varanusexanthamaticus (Savannah Monitor), Varanus niloticus (Nile Monitor),Varanus salvator (Water Monitor), Varanus prasinus (Tree Monitor),Varanus indicus (Indian Monitor), Varanus salvator (Water Monitor),Gekko gecko (Tokay Gecko), Eublepharis macularius (Leopard Gecko),Eublepharis Hemitheconyx (Fat tailed Gecko), Gekko ulikovski (GoldenGecko), Paroedura pictus (Madagascar Ground Gecko), Phelsuma abboti (DayGecko), Naultinus elegans (Green Tree Gecko), Pogona Vitticeps (BeardedDragons), Tupinambis teguixin (Tegu), Tupinambis merianae (Blue Tegu),Tiliqua scincoides (Skinks), Varanus indicus (Indian Monitor), Anoliscarolinensis (Green Anole), anolis sagrei (Brown Anole), Anolisequestris (Knight Anole), Anolis ricordii (Giant Anole), and Chamaelocalyptratus (Veiled Chameleon)

“Turtle” as used herein may be any turtle as discussed above, withparticular examples including but not limited to: Trachemys scripta(Sliders), Chrysemys picta (Painted Turtle), Graptemys geographica(Common Map Turtle), Graptemys pulchra (Alabama Map Turtle), Graptemysversa (Texas Map Turtle), Apalone ferox (Florida Softshell Turtle),Apalone mutica (Smooth Softshell Turtle), and Apalone spinifera (SpinySoftshell Turtle).

“Tortoise” as used herein includes but is not limited to tortoisefamilies Testudinidae, Emydidae, and Trionychidae, with particularexamples including but not limited to: Geochelone carbonaria (Red-FootedTortoise), Geochelone denticulata (South American yellow-footedtortoise), Geochelone radiata (Radiated tortoise, Geochelone sulcata(African Spurred Tortoise), Geochelone pardalis (Leopard Tortoise), andTestudo horsfieldii (Russian Tortoise).

“Crocodilian” as used herein may be any crocodilian species, includingthose in families Crocodyles and Crocodylidae, with particular examplesincluding but not limited to Caiman crocodilus (Spectacled Caiman),Alligator mississippiensis (American Alligator), and Osteolaemustetraspis (African Dwarf Crocodile).

“Retroviral vectors” and “lentiviral vectors” useful for carrying outthe present invention are known. In general such vectors comprise aviral particle enclosing viral nucleic acid which has been modified toincorporate the nucleic acid of interest to be carried into the targetanimal cells. Such vectors may be produced from the nucleic acids of anysuitable virus, including but not limited to the human immunodeficiencyvirus, feline immunodeficiency virus, equine infection anemia virus,Moloney murine leukemia virus, etc. Where the host specificity of avector is not appropriate for the target cells of the present inventionthat specificity may be changed to render it suitable for the presentinvention by the technique of pseudotyping as discussed below.

“Pseudotyped retroviral vectors” and “pseudotyped lentiviral vectors” asused herein are known. In general such vectors are those in which aviral capsid is changed, a viral capsid protein is replaced, anadditional viral capsid protein is added, etc., to change, alter, orbroaden the cell specificity of the virus so that it is internalized bythe desired target. Pseudotyped retroviral vectors are known.

“Expression sequence” as used herein typically refers to at least onepromoter, enhancer, response element, or combination thereof, includingthe response elements ordinarily associated with the correspondingpromoter and response elements from different promoters. Promoters,enhancers and response elements may be obtained from any suitablespecies, including reptile, amphibian (e.g., frog), avian (e.g.,chicken), and mammalian species (e.g., mouse), as well as from viruses.

“Therapeutic protein” as used herein may be any protein (includingpeptide, active protein fragments, and fusion proteins thereof) that hastherapeutic utility in treating human or animal disease. Examplesinclude but are not limited to insulin, glucagon-like peptide 1,antibodies, histocompatibility antigens, integrins, selectin inhibitors,growth factors, postridical hormones, nerve growth hormones, bloodclotting factors, adhesion molecules, bone morphogenic proteins,lectins, trophic factors, cytokines such as TGF-beta, IL-2, IL-4,alpha-IFN, beta-IFN, gamma-IFN, TNF, IL-6, IL-8, lymphotoxin, IL-5,Migration inhibition factor, GMCSF, IL-7, IL-3, monocyte-macrophagecolony stimulating factors, granulocyte colony stimulating factors,multidrug resistance proteins, other lymphokines, toxoids,erythropoietin, Factor VIII, amylin, TPA, dornase-alpha,alpha-1-antitrypsin, human growth hormones, nerve growth hormones, bonemorphogenic proteins, growth differentiation factors, neuregulin, ureaseand toxoids, and active fragments thereof, active peptides, and fusionproteins thereof. (see, e.g., US Patent Application Publication No.2006/0008532), as well as all of the therapeutic proteins listed inTable 1 of U.S. Pat. No. 6,946,134 and fusion proteins thereof.

“Reporter protein” as used herein includes but is not limited to pigmentproteins, fluorescent proteins, luminescent protein, enzymes and otherdetectable proteins. Specific examples include but are not limited tomelanin (including eumalanin and pheomelanin), carotenoids, pteridines,cyan biochromes, aequorin, luciferase, luciferin, blue fluorescentprotein, red fluorescent protein, ds red fluorescent protein, cyanfluorescent protein, yellow fluorescent protein, and green fluorescentprotein (including naturally occurring and mutant variants thereof).See, e.g., U.S. Pat. Nos. 7,034,141; 7,037,645; and 6,087,476. In someembodiments the visually detectable proteins such as the fluorescent orluminescent proteins are preferred. The foregoing is to be construed asinclusive of “enhanced” proteins, including but not limited to enhancedgreen fluorescent protein (eGFP), which are known in the art.

“Fluorescent or luminescent” as used herein to describe an animalphenotype means that at least a portion of the animal is visiblyfluorescent or luminescent to the ordinary human observer under usualconditions for observing fluorescence or luminescence (e.g., dimmed orreduced light, as in night-time or a darkened room, with or without theaddition of supplemental illumination of the animal with an ultra-violetor “black” light). The phenotype may be exhibited as a pattern offluorescence or luminescence on or through the skin of the animal,overall fluorescence or luminescence on or through the skin of theanimal, and/or fluorescence or luminescence of the eyes of the animal,etc.

A. Nucleic Acid Constructs and Vectors.

Heterologous nucleic acids of interest (e.g., those encoding atherapeutic, detectable or reporter protein) can be operativelyassociated with expression sequences operative in animals of theinvention and inserted into suitable vectors for infection animal cellsof the invention in accordance with known techniques, or variationsthereof that will be apparent to those skilled in the art. See, e.g.,U.S. Pat. Nos. 6,730,822; 6,380,458; and 5,932,780; see also US PatentApplication Publication No. 2006/010528.

Retroviral and lentiviral vectors are known. See, e.g., U.S. Pat. Nos.6,949,242; 6,838,280; 6,323,195; 6,303,116; 6,107,478; and 4,980,286.Where the vectors are replication deficient they can be produced inhelper cell lines in accordance with known techniques. See, e.g., U.S.Pat. Nos. 6,712,612; 5,124,263; 4,861,719; and 4,650,764. Pseudotypedvectors are known and retroviral and lentiviral vectors can bepseudotyped in accordance with known techniques. See, e.g., U.S. Pat.Nos. 6,863,884; 6,849,454; 6,544,779; 6,479,281; 6,117,681; 5,739,018;5,670,354; and 5,512, 421; see also J. Yee et al., Generation ofhigh-titer pseudotyped retroviral vectors with very broad host range,Methods Cell Biol. 43, 99-112 (1994); J. Burns et al., Vesicularstomatitis virus G glycoprotein pseudotyped retroviral vectors:Concentration to very high titer and efficient gene transfer intomammalian and nonmammalian cells, Proc. Natl Acad. Sci. USA 90, 833-8037(September 1993). In some embodiments, Vesicular stomatitis virus Gglycoprotein (VSV-G) pseudotype retroviral and lentiviral vectors arepreferred.

Expression sequences comprising promoters, enhancers, response elementsand combinations thereof (sometimes referred to as “regulatoryelements”) useful for carrying out the present invention are known. See,e.g., U.S. Pat. Nos. 6,730,822; 6,380,458; and 5,932,780. The expressionsequences may be constitutively active or inducible (e.g.,tissue-specific). Examples include but are not limited to the CMVpromoter, beta-actin promoter, the RSV promoter, crystallin promoterssuch as the alpha and delta crystallin promoters, the mylz2 promoter,the PGK promoter, the myosin heavy chain promoter, the myosin lightchain promoter, the cardiac myosin promoter, and the keratin promoter.See, e.g., U.S. Pat. Nos. 6,949,242; 6,897,045; and 6,784,289. In someembodiments crystallin promoters and/or enhancers, such as the deltacrystallin promoter and/or enhancers, are preferably included in theexpression sequence. See, e.g., L. Reneker et al., Invest. Opthalmol.Vis. Sci. 45, 4083-90 (2004); X. Li et al., Dev. Genet. 20, 258-66(1977). In some embodiments, where expression of a desired protein suchas a therapeutic protein into eggs of transgenic reptiles for subsequentharvesting is desired, ovalbumin promoters may be used. See, e.g., U.S.Pat. No. 6,730,822.

A nucleic acid encoding the expression product (sometimes also referredto as a protein of interest) is operatively associated with theexpression sequence to form what is sometimes referred to as an“expression cassette” in accordance with known techniques. If desired,insulators can be included upstream, downstream, or both upstream anddownstream from the expression sequence and associated nucleic acidencoding the expression product, in accordance with known techniques.See, e.g., U.S. Pat. Nos. 6,395,549; 6,229,070; 6,100,448; and5,610,053. Also if desired, scaffold attachment regions can be includedupstream, downstream, or both upstream and downstream from theexpression sequence and associated nucleic acid encoding the expressionproduct, in accordance with known techniques. See, e.g., U.S. Pat. Nos.6,239,328; 6,100,448; 5,773,695; and 5,773,689.

Vector particles containing vector nucleic acid with the with insertedexpression cassette is preferably concentrated in its injection solution(e.g., its growth media), for example to a titre of 10⁷ to 10⁹infectious units per milliliter of injection solution. A cationicpolymer such as 1,5-dimethyl-1,5-diazaundecamethylene polymethobromide,hexadimethrine bromide (commercially available as POLYBRENE® from SigmaAldrich) may be added to the injection solution to enhance retroviralinfection of the target cells, in accordance with known techniques (See,e.g., J. Manning et al., Appl. Microbiol. 22,1162 (1971)).

B. Egg Injection and Incubation.

Freshly laid reptile eggs are available from a variety of sources,including Bob Clark Captive Bred Reptiles Inc., 12316 Val Verde Drive,Oklahoma City, Okla. 73142 (telephone (405) 722-5017), Prehistoric Pets,18822 Brookhurst St., Fountain Valley, Calif., 92708 (telephone (714)964-3525), and collection from the wild.

Unlike bird eggs, reptile eggs appear to be position sensitive to theirsite of injection and incubation. Hence, freshly laid reptile eggs arepreferably marked to indicate the position at which they were laid byany suitable means (for example, a pen or pencil marking such as an “x”at the uppermost laid position thereof is suitable). The eggs can thenbe collected for vector administration.

Unlike bird eggs, reptile eggs rapidly absorb or release water from theatmosphere or their environment (in some cases, particulate media suchas vermiculite particulate media). Hence the contents of reptile eggsare at a positive pressure relative to the ambient atmosphere underconditions of high humidity. To avoid excess leakage of egg contentsafter injection, the eggs are preferably slightly dried prior toinjection to reduce the internal pressure therein. Drying may be carriedout by simply placing the eggs in a dry ambient environment or a dryparticulate media for a suitable duration, e.g., from five minutes toone day or more (e.g., about one hour for a python egg; about one dayfor a corn snake egg).

After drying the egg may then be injected. Injection may be carried outwith the aid of a dissection microscope with supplemental illuminationsuch as by fiber optic illumination, with injection being made into aregion such as the embryo proper or a blood vessel associated with theembryo. Injection is preferably carried out with a fine needle such as a30 gauge needle, with an injection volume of from 50 to 1000 microlitersof concentrated vector-containing injection solution typically beingappropriate, depending upon factors such as the concentration of thesolution, the size of the embryo, whether or not cationic polymer isincluded, etc. The eggs are preferably injected within one or two daysof being laid.

Since (unlike bird eggs) reptile eggs are leathery in texture, injectionmay be carried out directly through the shell without prior fracturingof the shell.

After injection the injection needle should be withdrawn slowly andafter needle withdrawal the injection hole is preferably immediately andrapidly sealed with rubber cement or other suitable sealant to preventalbumin from leaking through the hole (which would provide a site foropportunistic infection of the egg during subsequent incubation).

After injection the eggs are placed in an incubator. Unlike bird eggs,the reptile eggs should preferably be positioned in the incubator in aposition that corresponds to the position in which they were originallylaid (which may be identified by any suitable means such as a marking atthe uppermost portion thereof as noted above).

Reptile eggs are preferably incubated in or on a particulate media suchas vermiculite particulate media. The media is preferably dampened withthe addition of water during incubation. Depending upon the species, theeggs may be completely buried in the particulate media, partially buriedin the particulate media, or allowed to rest on top of the particulatemedia.

Also, unlike bird eggs which are “rocked” during incubation, reptileeggs should preferably be incubated without rocking, and are preferablymaintained as motionless as possible during their incubation to avoidtearing of or mechanical damage to the embryo (note that reptile embryosare attached to the interior of their shell while bird embryos are not).Reptile eggs are incubated for a relatively long time as compared tobird eggs, with incubation times of two months being typical. Inaddition, reptile eggs are incubated at a relatively low temperature ascompared to bird eggs, with incubation temperatures of 65 to 78 degreesFahrenheit (and in some cases up to 95 degrees Fahrenheit) beingtypical.

Procedures for the artificial incubation of reptile eggs are describedin, among other sources, B. Barnett, Artificial Incubation of ReptileEggs, Monitor—Journal of the Victorian Herpetological Society 9(2): 4-8(1998) and B. Clark, Python Egg Incubation, Reptiles Magazine (March2006).

C. Hatching and Subsequent Propagation.

Unlike chicks, reptiles upon hatch will tend to stay in their brokenshells for a period of time (e.g., several days). The reptiles shouldpreferably be allowed to remain in their shells until they emerge oftheir own accord and not forcibly removed.

First generation reptiles of the invention produced by injection withvector and incubation to hatch as described above will typically bechimeric, in that some cells of the reptiles will contain and expressthe heterologous nucleic acid while other cells will not. A portion ofsuch first generation reptiles will include germ-line transformedanimals in which the heterologous nucleic acid is incorporated into germcells and can be passed to or inherited by subsequent generations. Ifdesired, such germ-line transformed reptiles can be bred with otherreptiles, including wild-type reptiles or other genetically modifiedreptiles, to produce second generation reptiles of the invention inwhich all or essentially all cells contain the heterologous nucleic acidintegrated into the genome thereof. Second generation reptiles of theinvention can in turn be propagated in accordance with known techniques.

Reptiles of the invention subsequent to the first generation may beheterozygous or homozygous for the heterologous nucleic acid, dependingupon the choice of parents, as is known in the art.

First or subsequent generation reptiles of the invention in someembodiments exhibit the phenotype of fluorescence or luminescence.

First or subsequent generation reptiles of the invention in someembodiments exhibit the phenotype of expressing a heterologous proteinsuch as a therapeutic protein in eggs (e.g., into egg albumin) that arelaid by those reptiles.

In one embodiment of the invention, a first or subsequent generationreptile of the invention as a first (male or female) parent is crossedwith an albino or reduced-pigment reptile (e.g., a leucistic reptilesuch as a leucistic snake of any of the species noted above, leucisticball snake) of the same species so that progeny or subsequent generationreptiles are produced that exhibit both the fluorescent or luminescentphenotype and the albino or leucistic phenotype in combination.

First and subsequent generation reptiles of the invention express theexpression product in at least one of a desired tissue, including butnot limited to skin, muscle such as skeletal muscle, in the oviduct(e.g., for secretion of a therapeutic product into the albumin forsubsequent harvesting). See, e.g., U.S. Pat. No. 6,730,822.

Reptiles for breeding with transgenic reptiles of the invention areavailable from a variety of sources, including Bob Clark Captive BredReptiles Inc., Prehistoric Pets, and collection from the wild.

D. Utility.

Reptiles of the invention (including snakes, lizards, and crocodilians)are useful for testing for toxic, teratogenic, and/or oncogenic agentsin a manner analogous to the GLOFISH® fluorescent zebrafish ortransgenic frogs. Reptiles of the invention are particularly useful fortesting the effects, at various concentrations and under variousconditions emulating their natural environment, of androgens, estrogens,other endocrine disrupters, and pesticides, as such compounds may befound in the environment in which reptiles ordinarily reside.

Reptiles are utilized as test subjects for the identification of reptilerepellents as described in U.S. Pat. No. 6,689,397 to Clark. In Clark etal. a potential repellant is sprayed directly onto the snake and thebehavior of the snake thereafter observed (e.g., for locomotor or escapebehavior). Reptiles of the present invention (including snakes, lizards,and crocodilians such as crocodiles and alligators), particularly thosethat express a fluorescent or luminescent protein, can be utilized inlike manner, with the behavior of the reptile more readily observed dueto the enhanced visibility of the test subject. In an alternateembodiment, since reptiles of the invention are in some embodiments morereadily observed, the need for spraying a potentially noxious compoundon the reptile is obviated and instead the potential repellant can beapplied to a target or locus positioned in proximity to the reptile andthe behavior of the reptile in relation to the target (e.g., frequencyof approach or avoidance as compared to a like target to which thepotential repellant has not been applied) then observed. Further, suchtests can be carried out in an environment more natural to the animal,(such as a pond, penned marsh, grassy or wooded area, etc.) so that thetest is both less noxious to the animal and a more realistic indicatorof actual efficacy of the proposed repellant.

Venomous reptiles (including snakes) are maintained for the productionof venom which is used commercially as a biomedical testing reagent andto produce antivenin. Reptiles of the invention that express a visuallydetectable product (and are venomous) are useful for such purposes tofacilitate the handling and retrieval of such reptiles.

Transgenic reptiles of the invention that express a therapeutic proteinof interest are useful for the production and subsequent harvesting ofthe therapeutic protein. Such therapeutic proteins may be collected byany suitable means. In a preferred embodiment, where the therapeuticprotein is expressed into albumin of eggs laid by transgenic reptiles ofthe invention, the therapeutic protein may be collected, isolated andpurified directly from the albumin in accordance with known techniquessuch as described in U.S. Pat. No. 6,730,822. Pythons, which layrelatively large eggs, are particularly useful for this purpose.

Reptiles raised or maintains as pets, as teaching aids, for venomproduction, and as test subjects occasionally escape. For example, whena reptile is used to test environmental contaminants it may be placed ina several acre pen or pond containing a significant amount of naturalarea. When they escape it is desirable to catch and retrieve escapedanimals rather than permit their ultimate escape to the wild. Transgenicreptiles of the invention that carry and express a transgene encoding adetectable protein are accordingly useful to hobbyists, as well asresearchers studying toxicology, teratology and oncology, in that theyprovide subjects hat can be more easily retrieved in the event ofescape.

Since reptiles of the invention are more easily retrievable upon escapethan their wild-type counterparts, reptiles of the invention are morereadily housed in larger, more natural or wild-type pens that moreclosely emulates their natural environment when they are maintained forpurposes such as testing, venom production, etc.

Reptiles of the invention are commercially desirable by collectors,hobbyists and pet owners, such as those organized under various hobbyistand herpetological societies such as The Center for North AmericanHerpetology (1502 Medinah Circle, Lawrence, Kans. 66047 USA), thePhiladelphia Herpetological Society, the Tucson Herpetological Society,the Arizona Herpetological Association, etc.

Reptiles of the invention are useful as subjects or animal actors in thefilm industry, which use should be carried out in accordance withAmerican Humane's Guidelines for the Safe Use of Animals in Filmed Media(available from American Humane Film and Television Unit, 15366 DickensStreet, Sherman Oaks, Calif. 91403 USA (telephone (818) 501-0123).

Since the reptile brain is less highly developed than the brain ofmammalian species such as mice, rats, and rabbits, transgenic reptilesof the invention provide, in some instances, a preferable alternative asresearch subjects in those situations where research subjects arenecessary for biomedical research and toxocologic, teratologic, drugdiscovery, and oncogenic testing. See, e.g., U.S. Pat. No. 7,176,345 toKaelin et al.

The present invention is explained in greater detail in the followingnon-limiting examples.

Example 1 Preparation of MMLV Retroviral Vector

A DNA construct of, from 5′ to 3′, the Rous sarcoma virus promoter, thechicken beta-actin promoter, the chicken delta crystallin enhancer, andDNA encoding enhanced green fluorescence protein, was prepared. Theconstruct has the sequence between the Sadl and Pacl restriction sitesin the plasmid given in Table 1 below.

Briefly, a plasmid encoding the Rous sarcoma virus (RSV) promoter, thechicken beta-actin promoter, the chicken delta crystallin enhancer, andDNA encoding enhanced green fluorescence protein built on a pUCbackbone, was cut with the restriction enzymes Sacl and Pacl as shown inTable 1 below to specifically fractionate the portion of the plasmidencoding the Rous sarcoma virus (RSV) promoter, the chicken beta-actinpromoter, the chicken delta crystallin enhancer, and enhanced greenfluorescence protein. Subsequently, the DNA fragment was ligated intothe pFB plasmid (Stratagene, La Jolla Calif.). Subsequently, the plasmidwas transfected into 293T retroviral packaging cells usinglipofectamine-2000 (Invitrogen, Carlsbad Calif.) with pVPack-env plasmidencoding the viral coat proteins and pVpack GP encoding the viral gagand pol genes (Stratagene, LaJolla, Calif.). Retroviral supernatant wascollected from the cultures.

Similarly, the fragment encoding the Rous sarcoma virus (RSV) promoter,the chicken beta-actin promoter, the chicken delta crystallin enhancer,and enhanced green fluorescence protein was ligated into the pCDF1-MCS1™lentiviral cloning vector (System Bio, Mountain View Calif.). Theplasmid was transfected into 293T cells using lipfectamine-2000 withpPACKF1 Lentivector Packaging Kit that contained plasmids that providethe lentiviral coat proteins and the viral gag and pol genes (SystemBio, Mountain View Calif.). Tissue culture supernatant was collectedfrom the cultures.

TABLE 1 pMIEM (1 bp-4760 bp, direct) 4760 bp′CAGTGGGGTTGGCACTGCCACGCTCCGGATGCCGCGCTCTGATCCAACCCCATAATCAAGGGAACCCGAATTGCCCCATCATTGCCCCCACCACCCCCATCCTGCCGGGCCCTCACACCCCACGCTGCCTTCTGGTGACATTCCCCAGCCCAAACCCACGGCTTCATGGCTACCGCGGGGCATTTCCCATTGCCGCCCCATTATCAGCTCTGCACACCTCCCGCTGTACCCATGCCTCGTGGCTGCCCTTCTTTGACGTATAATCTTCTAATTAATACCCGGCCTTGTCAAAGTGGAGCACAAACGTTAATTAATTCCCCAGCAGGCAGGTAATTAACACTGTGACTCCCTTTTTGCTGCGAGTGGGGCTGATACAGAGAGATGTGGCACTATGGAGCCCACGGGGTCCTGGCACTGGGTGCCCACGGAGGTCCCCATGTGCAGCTTGGGAGCTTGGGCCCAGCTGCTCCCTGCTTGTGTGTTGGAGGTCGCTGAGTAGTGCGCGAGCAAAATTTAAGCTACAACAAGGCAAGGCTTGACCGACAATTGCATGAAGAATCTGCTTAGGGTTAGGCGTTTTGCGCTGCTTCGCGATGTACGGGCCAGATATACGCGTATCTGAGGGGACTAGGGTGTGTTTAGGCGAAAAGCGGGGCTTCGGTTGTACGCGGTTAGGAGTCCCCTCAGGATATAGTAGTTTCGCTTCTGCATAGGGAGGGGGAAATGTAGTCTTATGCAATACTCTTGTAGTCTTGCAACATGGTAACGATGAGTTAGCAACATGCCTTACAAGGAGAGAAAAAGCACCGTGCATGCCGATTGGTGGAAGTAAGGTGGTACGATCGTGCCTTATTAGGAAGGCAACAGACGGGTCTGACATGGATTGGACGAACCACTGAATTCCGCATTGCAGAGATATTGTATTTAAGTGCCTAGCTCGATACAATAAACGCCATTTGACCATTCACCACATTGGTGTGCACCTCCCAAGCTGCTCAGTGCATGCACGCTCATTGCCCATCGCTATCCCTGCCTCTCCTGCTGGCGCTCCCCGGGAGGTGACTTCAAGGGGACCGCAGGACCACCTCGGGGGTGGGGGGAGGGCTGCACACGCGGACCCCGCTCCCCCTCCCCAACAAAGCACTGTGGAATCAAAAAGGGGGGAGGGGGGATGGAGGGGCGCGTCACACCCCCGCCCCACACCCTCACCTCGAGGTGAGCCCCACGTTCTGCTTCACTCTCCCCATCTCCCCCCCCTCCCCACCCCCAATTTTGTATTTATTTATTTTTTAATTATTTTGTGCAGCGATGGGGGCGGGGGGGGGGGGGGCGCGCGCCAGGCGGGGCGGGGCGGGGCGAGGGGCGGGGCGGGGCGAGGCGGAGAGGTGCGGCGGCAGCCAATCAGAGCGGCGCGCTCCGAAAGTTTCCTTTTATGGCGAGGCGGCGGCGGCGGCGGCCCTATAAAAAGCGAAGCGCGCGGCGGGCGGGAGTCGCTGCGCGCTGCCTTCGCCCCGTGCCCCGCTCCGCCGCCGCCTCGCGCCGCCCGCCCCGGCTCTGACTGACCGCGTTACTCCCACAGGTGAGCGGGCGGGACGGCCCTTCTCCTCCGGGCTGTAATTAGCGCTTGGTTTAATGACGGCTCGTTTCTTTTCTGTGGCTGCGTGAAAGCCTTAAAGGGCTCCGGGAGGGCCCTTTGTGCGGGGGGGAGCGGCTCGGGGGGTGCGTGCGTGTGTGTGTGCGTGGGGAGCGCCGCGTGCGGCTCCGCGCTGCCCGGCGGCTGTGAGCGCTGCGGGCGCGGCGCGGGGCTTTGTGCGCTCCGCAGTGTGCGCGAGGGGAGCGCGGCCGGGGGCGGTGCCCCGCGGTGCGGGGGGGCTGCGAGGGGAACAAAGGCTGCGTGCCGGGGTGTGTGCGTGGGGGGGTGAGCAGGGGGTGTGGGCGCGGCGGTCGGGCTGTAACCCCCCCCTGCACCCCCCTCCCCGAGTTGCTGAGCACGGCCCGGCTTCGGGTGCGGGGCTCCGTGCGGGGCGTGGCGCGGGGCTCGCCGTGCCGGGCGGGGGGTGGCGGCAGGTGGGGGTGCCGGGCGGGGCGGGGCCGCCTCGGGCCGGGGAGGGCTCGGGGGAGGGGCGCGGCGGCCCCCGGAGCGCCGGCGGCTGTCGAGGCGCGGCGAGCCGCAGCCATTGCCTTTTATGGTAATCGTGCGAGAGGGCGCAGGGACTTCCTTTGTCCCAAATCTGTGCGGAGCCGAAATCTGGGAGGCGCCGCCGCACCCCCTCTAGCGGGCGCGGGGCGAAGCGGTGCGGCGCCGGCAGGAAGGAAATGGGCGGGGAGGGCCTTCGTGCGTCGCCGCGCCGCCGTCCCCTTCTCCATCTCCAGCCTCGGGGCTGTCCGCAGGGGGACGGCTGCCTTCGGGGGGGACGGGGCAGGGCGGGGTTCGGCTTCTGGCGTGTGACCGGCGGGGTTTATATCTTCCCTTCTCTGTTCCTCCGCAGCCCCCAAGCTCCCACAGTTTTACTTGAATGTGGCACTGAGAGATTTTTAGGAGAATATATCAATAATGCATTTGAACATATCCTTTAATTTTAATTACTCTCAGGGGGATAAACTTTTGGGAGGAAGATTTGTTGGAAGCACAGATCCCATCATGGAGATTCTCAGCTCTTCTATATCCACTGAGCAGAGACTGACTGAAGTTGATGGGGATCGGGATCCACCGGTCGCCACCATGGTGAGCAAGGGCGAGGAGCTGTTCACCGGGGTGGTGCCCATCCTGGTCGAGCTGGACGGCGACGTAAACGGCCACAAGTTCAGCGTGTCCGGCGAGGGCGAGGGCGATGCCACCTACGGCAAGCTGACCCTGAAGTTCATCTGCACCACCGGCAAGCTGCCCGTGCCCTGGCCCACCCTCGTGACCACCCTGACCTACGGCGTGCAGTGCTTCAGCCGCTACCCCGACCACATGAAGCAGCACGACTTCTTCAAGTCCGCCATGCCCGAAGGCTACGTCCAGGAGCGCACCATCTTCTTCAAGGACGACGGCAACTACAAGACCCGCGCCGAGGTGAAGTTCGAGGGCGACACCCTGGTGAACCGCATCGAGCTGAAGGGCATCGACTTCAAGGAGGACGGCAACATCCTGGGGCACAAGCTGGAGTACAACTACAACAGCCACAACGTCTATATCATGGCCGACAAGCAGAAGAACGGCATCAAGGTGAACTTCAAGATCCGCCACAACATCGAGGACGGCAGCGTGCAGCTCGCCGACCACTACCAGCAGAACACCCCCATCGGCGACGGCCCCGTGCTGCTGCCCGACAACCACTACCTGAGCACCCAGTCCGCCCTGAGCAAAGACCCCAACGAGAAGCGCGATCACATGGTCCTGCTGGAGTTCGTGACCGCCGCCGGGATCACTCTCGGCATGGACGAGCTGTACAAGTAAAGCGGCCGCGACTCTAGATCATAATCAGCCATACCACATTTGTAGAGGTTTTACTTGCTTTAAAAAACCTCCCACACCTCCCCCTGAACCTGAAACATAAAATGAATGCAATTGTTGTTGTTAACTTGTTTATTGCAGCTTATAATGGTTACAAATAAAGCAATAGCATCACAAATTTCACAAATAAAGCATTTTTTTCACTGCATTCTAGTTGTGGTTTGTCCAAACTCATCAATGTATCTTAAGGCGTAAATTGTAAGCGTTAATGATCCCCGGGTACCGAGCTCGAATTCGTAATCATGTCATAGCTGTTTCCTGTGTGAAATTGTTATCCGCTCACAATTCCACACAACATACGAGCCGGAAGCATAAAGTGTAAAGCCTGGGGTGCCTAATGAGTGAGCTAACTCACATTAATTGCGTTGCGCTCACTGCCCGCTTTCCAGTCGGGAAACCTGTCGTGCCAGCTGCATTAATGAATCGGCCAACGCGCGGGGAGAGGCGGTTTGCGTATTGGGCGCTCTTCCGCTTCCTCGCTCACTGACTCGCTGCGCTCGGTCGTTCGGCTGCGAATGAATCGGCCAACGCGCGGGGAGAGGCGGTTTGCGTATTGGGCGCTCTTCCGCTTCCTCGCTCACTGACTCGCTGCGCTCGGTCGTTCGGCTGCGGCGAGCGGTATCAGCTCACTCAAAGGCGGTAATACGGTTATCCACAGAATCAGGGGATAACGCAGGAAAGAACATGTGAGCAAAAGGCCAGCAAAAGGCCAGGAACCGTAAAAAGGCCGCGTTGCTGGCGTTTTTCCATAGGCTCCGCCCCCCTGACGAGCATCACAAAAATCGACGCTCAAGTCAGAGGTGGCGAAACCCGACAGGACTATAAAGATACCAGGCGTTTCCCCCTGGAAGCTCCCTCGTGCGCTCTCCTGTTCCGACCCTGCCGCTTACCGGATACCTGTCCGCCTTTCTCCCTTCGGGAAGCGTGGCGCTTTCTCATAGCTCACGCTGTAGGTATCTCAGTTCGGTGTAGGTCGTTCGCTCCAAGCTGGGCTGTGTGCACGAACCCCCCGTTCAGCCCGACCGCTGCGCCTTATCCGGTAACTATCGTCTTGAGTCCAACCCGGTAAGACACGACTTATCGCCACTGGCAGCAGCCACTGGTAACAGGATTAGCAGAGCGAGGTATGTAGGCGGTGCTACAGAGTTCTTGAAGTGGTGGCCTAACTACGGCTACACTAGAAGAACAGTATTTGGTATCTGCGCTCTGCTGAAGCCAGTTACCTTCGGAAAAAGAGTTGGTAGCTCTTGATCCGGCAAACThe construct set forth in Table 1 was inserted into the pFB plasmid.Retroviral vector (a modified Moloney murine leukemia virus) preparedusing the VIRAPORT® retroviral gene expression system from Stratagene(11011 N. Torrey Pines Road, La Jolla, Calif. 92037 USA). Retroviralsupernatant was concentrated for subsequent administration as describedfurther below.

Examples 2-3 Transformation of Ball Pythons

A. Materials and Methods.

Ball python eggs were procured within 24 hours of laying. Subsequently,eggs were candled eggs to locate the embryo which is usually lying onthe bottom side of the egg using a fiber optic light. Eggs were placedin a position where the embryo was oriented at the top of the egg.

Mix pFB-hrGFP retroviral supernatant (Stratagene, La Jolla Calif.,Catalog number 972002) with polybrene at a final concentration of 10micrograms per microliter. Inject 100 to 300 microliters of retroviralsupernatant with POLYBRENE® cationic polymer (10 micrograms per ml)directly into the embryo that is illuminated using fiber optic lightingusing a 30 gauge needle and a 1 cc syringe. Slowly remove the needle andclose hole with rubber cement. Turn embryo over, place on top of moistvermiculite and incubate the embryo at a temperature of 88-94° F. forabout 60 days, until hatching.

Maintain snakes until shedding and collect skin. One skin was obtainedfrom a non-transgenic ball python as a negative control reaction.

Procedure for DNA extraction of Wild-type Ball Python snake skin: 0.04grams of skin was chopped with scissors and placed sample in a sterile1.5 mL micro centrifuge tube. Skin was washed with 1.0 mL of 0.9% NaClsolution, vortexed followed by centrifugation for 10 minutes, at13.2×1000 rpm, to separate the supernatant from the sample. Thesupernatant was then removed and 1 mL of cell dispersion solutioncontaining collagenase was added. It has been found that snake cast-offskin reacts to a collagenase treatment (200 mM Tris/HCl buffer (pH 8.0),and 600 units collagenase) thereby increasing the molecular weight ofthe extracted DNA (Eguchi and Eguchi 2000). This solution was thenvortexed to mix contents thoroughly and incubated for 16 hours in a 37°C. shaker incubator at 225 rpm. The suspension was then centrifuged for10 minutes, at 13.2×1000 rpm and the supernatant discarded. In order tofurther release the DNA from the snake skin, 1 mL of Proteinase K (10 mMTris/HCL (pH 8.0), 1 mM EDTA, 1% SDS, and 30 units of Proteinase K) wasadded to the micro centrifuge tube and incubated for an additional 16hrs in a 37° C. shaker incubator at 150 rpm. The skin solution wascentrifuged for 10 minutes at 13.2×1000 rpm and the supernatant wasdiscarded. Subsequently the DNA was isolated from the solution usingEasy-DNA™ Kit (Invitrogen) following protocol #3 from the manual. Toisolate the DNA, 350 microliters of Solution A (IsolationSolution—provided with Kit) was added to the pellet, and the mixture wasincubated at 65° C. for 10 minutes. Subsequently, 150 microliters ofSolution B (precipitation solution-provided with kit) was added to thesuspension, and the solution was vortexed for between 10 seconds and 1minute. 500 microliters of chloroform was added to the suspension and itwas vortexed between 10 seconds and one minute. The suspension wasplaced in the microfuge and microfuged for 20 minutes at the highestspeed setting. The upper phase of the solution was removed, placed in afresh microfuge tube, and mixed with 1 mL of cold (4° C.) 100% ethanol.The solution was incubated for 30 minutes on ice. The solution wasmicrocentrifuged at the top speed of the microfuge for 15 minutes at 4°C. The liquid phase was removed from the DNA pellet, and the DNA pelletwas washed with 80% ethanol. The DNA pellet was resuspended in 100microliters of Tris-EDTA buffer containing 2 mg/ml RNAse A, andincubated at 37° C. for 30 minutes before storage at 4° C. 100microliters of the DNA was solution was extracted with a concentrationof 94.23 ng/ul.

Procedure for DNA extraction of Transgenic Ball Python snake skin: Theskin was processed in three sections (⅓ each): Head, Tail, andMid-section, Dorsal and Ventral sections, a total of six samples.

TABLE 2 Transgenic Snake 1: Dorsal Ventral Head 0.03 grams 0.03 gramsMid-Section 0.03 grams 0.04 grams Tail 0.03 grams 0.03 grams

TABLE 3 Transgenic Snake 2: Dorsal Ventral Head 0.12 grams 0.05 gramsMid-Section 0.10 grams 0.09 grams Tail 0.06 grams 0.06 gramsThe samples were processed using the same procedure as the wild-type DNAextraction procedure.

PCR verification of eGFP in the transgenic Ball-Python DNA: The PCRmixture contained 150 ng of sample DNA, 50 mM Tris-HCL (pH 8.3), 1 mMMgCl2, 100 mM KCL, 3 mg/mL highly purified BSA, 1× Master Amp withBetaine (EPICENTRE®), 2 mM dNTP, 50 pmol of each primer (eGFP-R15-TGGCGGATCTTGAAGTTCAC-3, F1 5-TCAAGGAGGACGGCAACATC-3), and 15 U of Taqpolymerase. The samples were the amplified using a MJ Research PTC-200Peltier Thermo Cycler with the following conditions, a hotstart at 95°C. for 3 min, followed by 30 cycles with the following conditions, 95°C. 45 sec, 58° C. 45 sec, 70° C. 1 min 30 sec. The extracted DNA andamplified DNA were analyzed by spectrometry and by 1.2% agarose gelelectrophoresis in Tris-Acetate EDTA buffer (TAE). Procedure to verify118 bp band and 600 bp amplified band: The amplified PCR product usingsample Mid-Ventral was fractionated through an agarose gel and thepredicted 118 bp band was removed from the gel and cloned into thepGEM-T plasmid using pGEM-T easy kit (Promega, Madison Wis.). The PCRproducts and linearized plasmid were mixed with the T4 ligase buffer (3Wiess Units/microliter), and the ligation buffer provided by the kit.The plasmids were introduced into competent bacteria (JM109 Cells) usingheat, and grown under ampicillin selection. The plasmid DNA was isolatedfrom bacterial cultures using a QIAfilter™ Plasmid DNA Purification kit(catalog number 12262). The presence of the PCR products in the plasmidswere verified by digesting the plasmid with using ECO R1 to verify bandinsertion. The plasmid was sent to DNA sequencing core facility at theUniversity of Florida to sequence of the insert.

TABLE 4 Blast Results of Insert Compared to Clontech pEGFP vector Score= 229 bits (119), Expect = 5e−56 Identities = 119/119 (100%), Gaps =0/119 (0%) Strand = Plus/Plus Query 679TTCAAGGAGGACGGCAACATCCTGGGGCACAAGCTGGAGTACAACTACAACAGCCACAAC 738|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| Sbjct 45TTCAAGGAGGACGGCAACATCCTGGGGCACAAGCTGGAGTACAACTACAACAGCCACAAC 104 Query739 GTCTATATCATGGCCGACAAGCAGAAGAACGGCATCAAGGTGAACTTCAAGATCCGCCA 797||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| Sbjct 105GTCTATATCATGGCCGACAAGCAGAAGAACGGCATCAAGGTGAACTTCAAGATCCGCCA 163 QueryClontech EGFP vector EGFP between 289 and 1008. Therefore, amplifiedsequence is within the EGFP gene.B. Results: Ball Python Experiment.

Five Injected Embryos Hatch from a total of 21 injected (attributedreduced hatchability to novice-level of experience incubating ballpython eggs). Incubation conditions are slightly different between aball python and a corn snake.

Snakes were maintained until skin could be obtained from the naturalshedding process and the skin was analyzed for the presence of GFP.

FIG. 1. PCR results from potential Transgenic Ball python skin. Allsamples indicate a predicted 118 bp PCR product and a 600 bp PCRproduct. Water control lane shows no amplification products.

FIG. 2. PCR Results from two potential transgenic ball pythons (lanes2-7 and lanes 11-16), positive control plasmid (Lane 10), negativecontrol wild-type ball python DNA (lane 9), and water negative control(lane 10). FIG. 2 is a repeat of data presented in FIGS. 1 and 3.Therefore, we have identified two animals with GFP DNA in their skin.

FIG. 3 PCR results from the second transgenic ball python.

FIGS. 4 and 5 provide verification of DNA integrity of the DNA templateused to generate the data presented in FIGS. 1 and 2.

TABLE 5 Blast Results of Insert Compared to Clontech pEGFP vector. Score= 229 bits (119), Expect = 5e−56 Identities = 119/119 (100%), Gaps =0/119 (0%) Strand = Plus/Plus Query 679TTCAAGGAGGACGGCAACATCCTGGGGCACAAGCTGGAGTACAACTACAACAGCCACAAC 738|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| Sbjct 45TTCAAGGAGGACGGCAACATCCTGGGGCACAAGCTGGAGTACAACTACAACAGCCACAAC 104 Query739 GTCTATATCATGGCCGACAAGCAGAAGAACGGCATCAAGGTGAACTTCAAGATCCGCCA 797||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| Sbjct 105GTCTATATCATGGCCGACAAGCAGAAGAACGGCATCAAGGTGAACTTCAAGATCCGCCA 163

Query Clontech EGFP vector EGFP between 289 and 1008. Therefore,amplified sequence is within the EGFP gene.

118 bp from proposed transgenic snake match 100% homology with predictedEGFP sequence.

Example 4 Preparation of FIV Lentiviral Vector

The construct described in Table 1 of example 1 above is inserted intoplasmid pCDF1-MCS1 (available from System Biosciences (SBI), 211 SouthWhisman Road, Mountain View, Calif. 94041 (Tel: 650-968-2200)) and viralparticles generated in accordance with known techniques (See Example 1).

Vector is concentrated and used to infect Ball Python in like manner asdescribed in Examples 2-3 above.

Example 5 Transformation of Corn Snakes

Corn snake eggs are obtained and transfected in like manner as describedfor Ball Python in Examples 1-4 above, but with a slightly smallerinjection volume (50-100 microliters).

Experiment #1: Poke hole in egg shell of corn snake eggs with a 30 gaugeneedle and seal with rubber cement compare manipulated to intact eggs.

Clutch #1 8 total embryos 4 manipulated 4 intact. 3 manipulated hatchand 3 intact hatch.

Clutch #2 15 total embryos. 8 manipulated 7 intact controls. 8manipulated hatched. 6 intact hatched.

Clutch #3 14 total embryos. 9 manipulated 5 intact controls. 8manipulated hatch. 5 intact hatch.

Overall Hatch Rate Manipulated 95% Intact 87.5%.

Corn snake eggs are incubated to hatch buried in damp vermiculiteparticulate media for 55 to 70 days at a temperature of from 72 to 84°F.

Example 6 Transformation of King Snakes

King snake eggs are obtained and transfected in like manner as describedfor Ball Python in Examples 1-4 above, but with a slightly smallerinjection volume.

Specifically retroviral supernatent (pFB system) encoding the eGFP genederived from the PMIEM plasmid and driven by theRSV/beta-actin/delta-crystallin promoter was generated aftertransfecting 293T cells. The supernatants were frozen and stored at −80°C. Retroviral supernatent was thawed and mixed with polybrene 10micrograms per mL supernatent. The supernatent was either concentratedor used as unconcentrated virus. When virus was concentrated, theVIRABIND™ Lentivirus Purification Kit (Cell Biolabs, San Diego Calif.)that employs a purification filter technology was used. The lentiviruspurification kit is compatible with both lentiviral and retroviralvectors. Briefly the LTV purification filter is washed with Wash buffer(Catalog 90210), and approximately 10 mL of retroviral cell culturesupernatent is applied to the LTV purification filter, the filter iswashed with the Wash buffer. Subsequently, the virus was eluted with 2mL of elution buffer (25 mM Tris pH 7.5, 2.5 mM Mg2Cl, 1 Mm NACl). Theembryos were injected with virus suspended in the elution buffer.

12 embryos were injected with approximately 50 microliters ofconcentrated virus in the first king snake experiment and the site ofinjection was sealed with rubber cement. Of the 12 that were injected, 4were incubated through hatching to generate viable offspring. Incomparison, six of eight intact control embryos were successfullyincubated through hatching. In the second king snake experiment 14 kingsnake embryos were injected with unconcentrated retroviral supernatent,and the injection site was sealed with paraffin wax. Three of the 14injected embryos successfully hatched to produce viable offspring.However, zero of six control embryos hatched suggesting that incubationconditions were not optimal.

King snake eggs are incubated to hatch buried in damp vermiculiteparticulate media for 50 to 65 days at a temperature of from 82 to 85°F.

The foregoing is illustrative of the present invention, and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. A transgenic snake that expresses a heterologous protein expressionproduct, comprising an expression sequence operably linked to a sequenceencoding said heterologous expression product, wherein the sequenceencoding the expression product is integrated into the genome of thesnake, wherein the heterologous protein is expressed in detectablequantities in said snake.
 2. The transgenic snake of claim 1, whereinsaid expression product is a reporter protein.
 3. The transgenic snakeof claim 1, wherein said expression product is a fluorescent orluminescent protein.
 4. The transgenic snake of claim 1, wherein saidsnake has a phenotype of fluorescence or luminescence not found in thecorresponding wild-type snake.
 5. The transgenic snake of claim 1,wherein said expression product is a therapeutic protein.
 6. Thetransgenic snake of claim 1, wherein said expression product isexpressed in skin, skeletal muscle or both.
 7. A transgenic snake thatexpresses a heterologous protein expression product, comprising anexpression sequence operably linked to a sequence encoding saidheterologous expression product, wherein the sequence encoding theexpression product is integrated into the genome of the snake; whereinsaid protein expression product is a fluorescent or luminescent proteinexpressed in detectable quantities in said snake so that said snake hasa phenotype of fluorescence or luminescence not found in thecorresponding wild-type snake; and wherein said snake is a corn snake,ball python, or Kingsnake.
 8. The transgenic snake of claim 7, whereinsaid expression product is expressed in skin, skeletal muscle or both.9. The transgenic snake of claim 7, wherein said snake is an albino orleucistic snake.
 10. A method of screening a compound or composition forsnake repellent activity, comprising applying a candidate compound orcomposition to a target and then observing the behavior of a snakeaccording to claim 8 in relation to said target, wherein avoidance ofsaid target by said snake indicates said compound or composition hassnake repellent activity.
 11. A method of making a transgenic snake,comprising the steps of: (a) providing an expression sequence operablylinked to a sequence encoding a heterologous protein expression product,(b) transforming a snake in ovo with said expression sequence byinjecting directly into a snake embryo a retroviral vector comprising anexpression sequence operably linked to a sequence encoding saidheterologous protein expression product, so that the sequence encodingthe expression product is integrated into the genome of the snake, andthen (c) incubating said snake to hatch to produce a chimeric firstgeneration snake.
 12. The method of claim 11, wherein said expressionproduct is a reporter protein or therapeutic protein.
 13. The method ofclaim 11, wherein said expression product is a fluorescent orluminescent protein and said chimeric first generation snake has aphenotype of fluorescence or luminescence not found in the correspondingwild-type snake.